There is commonly known two types of foundations, shallow foundations and deep foundations. Shallow foundations are usually embedded a meter or so into soil. One common type is the spread footing which consists of strips or pads of concrete (or other materials) which extend below the frost line and transfer the weight from walls and columns to the soil or bedrock. Another common type of shallow foundation is the slab-on-grade foundation where the weight of the building is transferred to the soil through a concrete slab placed at the surface. Deep foundations are used to transfer a load from a structure through an upper weak layer of soil to a stronger deeper layer of soil. There are different types of deep foundations including helical piles, impact driven piles, drilled shafts, caissons, piers, and earth stabilized columns. The naming conventions for different types of foundations vary between different engineers. Historically, piles were wood, later steel, reinforced concrete, pre-tensioned concrete, and/or concrete masonry units.
Insulating the foundation building structures, like residential homes and commercial buildings, is important for many reasons. Insulation for a building's foundation wall can control the heat exchange between the ground and the interior of the foundation wall, thus saving energy. Insulation can also provide a hydrostatic pressure barrier between the surrounding earth and the foundation wall, thus providing structural advantages. Also, protecting the foundation wall from water saturation is important, especially below grade, or below ground, where dampness and moisture is present year round. Thus, a material for insulating and providing an adequate drainage path for a building's foundation wall is desired.
One known product that may be used for insulating and providing a drainage path for a foundation wall is the use of fiberglass boards. The fiberglass boards are applied against the foundation wall after a waterproof coating has been applied. The fiberglass boards can provide a thermal resistance for insulating the foundation, they can provide drainage paths to prevent dampness and moisture from rotting the structure, and they can provide a compression resistance to relieve the structure from some of the hydrostatic pressure from the surrounding earth. However, all of the aforementioned properties could be improved to provide an insulation and drainage material that provides better thermal resistance, better drainage, and better compression resistance.
In addition to these desired improvements, the fiberglass boards are very dangerous to manually install as the glass from the fiberglass can be very irritating and damaging to the installer's skin. Also, the fiberglass boards are sensitive to sunlight, which means they will degrade with any UV exposure. Thus, the fiberglass boards require the foundation to be immediately back filled when installed. Moreover, the fiberglass boards are of a laminar structure with fibers running in the x and y planes, which does not provide for an ideal drainage path across the boards. Also, the fiberglass boards do not stand up well to the changing hydrostatic pressures when back filled, i.e., the fiberglass board tends to break down or be crushed under the constantly changing pressure from the surrounding earth. Finally, the fiberglass boards are bonded with phenolic and formaldehyde resins, which are well known to be dangerous to the environment.
Another product that may be used for insulating and providing a drainage path for a foundation wall is the use of dimpled plastic sheets. Like the fiberglass boards, the dimpled plastic sheets are applied against the foundation wall. The dimpled plastic sheets can either be applied directly to the foundation wall or be applied after a waterproof membrane. When applied after the waterproofing membrane, the dimples face towards the soil with a filter fabric typically either glued or thermally bonded to the dimple side to keep the drainage area clear of soil particles. However the dimpled plastic sheet provides no thermal resistance. In addition, the dimpled plastic sheets can easily be crushed or damaged on the job site and are more difficult to install. Furthermore, when installing with a waterproof membrane, the membrane must be allowed to cure & dry for 24-36 hours before the dimple drain board can be applied and secured, thus adding extra time and delay to the building process. Another disadvantage to the dimpled plastic sheets is that they need to be secured to the foundation wall by mechanical fasteners, like nails, which have to puncture the waterproofing membrane. Dimpled plastic sheets can also be secured by glues or adhesives, but these glues and adhesives are relatively expensive.
The instant invention is designed to provide an insulation and drainage material for a foundation that address all the problems mentioned above.